The present invention refers to a method and a device for embossing and printing a web of flexible material, such as paper and nonwoven material. Especially it refers to production of tissue products such as toilet and kitchen paper, paper towels, handkerchiefs, wiping material and the like. The invention further refers to an embossed and printed web of flexible material, such as paper and nonwoven.
It is common to emboss and print tissue products. Embossing is a way of increasing the bulk of the paper and it also gives a three-dimensional structure to the paper, which improves the absorption properties and also the aesthetic appearance of the tissue product. Embossing may further be a way of laminating two or more tissue paper plies together, at which a mechanical joining of the plies occur in the embossing sites. Embossing is often combined with gluing for laminating tissue paper plies. This is for example disclosed in U.S. Pat. No. 3,414,459, in which laminating of tissue plies by a combined embossing and gluing procedure is shown. The embossing is of so called foot-to-foot type according to which the raised protuberances of the embossed tissue plies are joined together. In U.S. Pat. No. 3,867,225 there is also disclosed a combined embossing and gluing process, but where the embossing is of so called nested type according to which the raised projections of one tissue ply will rest in and be joined to the depressions of the opposite ply.
Printing of tissue paper is often made for aesthetical reasons. The printing pattern could be any pattern including more or less continuous lines, line segments, dots, trademarks, logotypes, symbols, fantasy characters etc. One conventional way of embossing and printing a tissue paper is to perform the embossing first and subsequently the printing. This method will result in that the printing colorant will be located substantially only on the raised projections of the embossing pattern. An example of such method is found in U.S. Pat. No. 5,339,730.
According to an alternative method the printing of one tissue ply is made first and subsequently this tissue ply is embossed and laminated with another tissue ply. A drawback with such a method is that the colorant is not always completely dry before the embossing, which means a risk that the printing will be blurred.
In both these methods there is a risk that the embossing deteriorate the quality of the printing.
The object of the present invention is to provide a method for producing a printed and embossed web of flexible material, such as paper and nonwoven material of an improved quality especially printing quality. According to one embodiment the invention refers to printed and embossed tissue paper, which may be a one-ply or multi-ply tissue product.
This object has according to one embodiment of the invention been provided by embossing the web by bringing it into a first nip between a pattern roll and an impression roll, said pattern roll having a three dimensional pattern of alternating raised and recessed portions, said three dimensional pattern being interrupted by substantially smooth areas, so that the web will be embossed in selected areas while leaving other areas substantially unembossed;
subsequently bringing the web into a second nip between said impression roll and a printing roll carrying a colorant in a selected pattern, said pattern roll and printing roll are synchronized so that said colorant is transferred at least mainly to unembossed areas of the web in said selected pattern.
According to an alternative embodiment of the invention the method comprises: printing the web in a selected pattern by bringing it into a first nip between an impression roll and a printing roll carrying a colorant in the selected pattern; subsequently embossing the web by bringing it into a second nip between a pattern roll and an impression roll, said pattern roll having a three dimensional pattern of alternating raised and recessed portions, said three dimensional pattern being interrupted by substantially smooth areas, so that the web will be embossed in selected areas while leaving other areas substantially unembossed; said pattern roll and printing roll are synchronized so that embossing occurs at least mainly in the areas of the web that are not printed in said selected pattern.
The web that undergoes the embossing and printing steps can be a one-ply or a multi-ply material. The multi-ply web can be a laminated web in which plies have been joined by for example by gluing and/or embossing. The multi-ply web can alternatively comprise two or more plies which have not been joined, and which will be joined together by the embossing step and an optional subsequent gluing step or the like.
According to a preferred embodiment the pattern roll is of a harder material than the impression roll, which is of a non-rigid material, so that the three dimensional pattern on the pattern roll will cause temporary or permanent impressions in the surface of the impression roll.
The non-embossed areas of the web entering the second press nip will present raised areas with respect to the printing roll adapted to receive the colorant in said selected printing pattern, while said impression roll serves as a counter roll during the printing.
The invention further refers to a device for embossing and printing a web of flexible material, such as paper and nonwoven material, said device comprising an embossing roll having a three dimensional pattern of alternating raised and recessed portions, said three dimensional pattern being interrupted by relatively smooth areas; a printing roll adapted to carry a colorant in selected pattern, said embossing roll and said printing roll being synchronized, an impression roll cooperating with the embossing roll and the printing roll.
In addition the invention refers to a printed and embossed web of flexible material, such as a paper and nonwoven, wherein the web is embossed in selected areas and that other areas are relatively smooth and non-embossed and that the web is printed in a selected pattern at least mainly in said smooth and non-embossed areas.
According to one embodiment at least 50% of the printed area of said selected printing pattern is located on the non-embossed areas of the web. According to further embodiments at least 75% and preferably at least 90% of the printed area of said selected printing pattern is located on the smooth non-embossed portions of the web. According to an additional embodiment substantially all printed area of said selected printing pattern is located on the smooth non-embossed portions of the web.
In a preferred embodiment said selected embossed areas are arranged as groups of embossment sites having said substantially smooth and unembossed areas between said groups of embossment sites, and that at least some of said smooth and unembossed areas have an uninterrupted surface area of at least 1 cm2, preferably at least 1.5 cm2 and more preferably at least 2 cm2 having no embossment sites thereon.
The paper web may in one embodiment besides said selected printing pattern be provided with other printing patterns optionally configured on the paper web.
The web of material is according to one embodiment tissue paper, which may be one-ply or multi-ply tissue product.
Further features of the invention are disclosed in the following description and in the claims.